Evolution of Philodendron (Araceae) species along Neotropical biomes

Abstract

Philodendron is the second most diverse genus of the Araceae, a tropical monocot family with significant morphological diversity along its wide geographic distribution in the Neotropics. Although evolutionary studies of Philodendron were conducted in recent years, the phylogenetic relationship among its species remains unclear. Additionally, analyses conducted to date suggested the inclusion of all American representatives of a closely related genus, Homalomena, within the Philodendron clade. A thorough evaluation of the phylogeny and timescale of these lineages is thus necessary to elucidate the tempo and mode of evolution of this large Neotropical genus and to unveil the biogeographic history of Philodendron evolution along the Amazonian and Atlantic Rain Forests, as well as open dry forests of South America. To this end, we have estimated the molecular phylogeny for 68 Philodendron species, which consists of the largest sampling assembled to date aiming the study of the evolutionary affinities. We have also performed ancestral reconstruction of species distribution along biomes. Finally, we contrasted these results with the inferred timescale of Philodendron and Homalomena lineage diversification. Our estimates indicate that American Homalomena is the sister clade to Philodendron. The early diversification of Philodendron took place in the Amazon Forest from Early to Middle Miocene, followed by colonization of the Atlantic Forest and the savanna-like landscapes, respectively. Based on the age of the last common ancestor of Philodendron, the species of this genus diversified by rapid radiations, leading to its wide extant distribution in the Neotropical region.

Phylogeny and diversification history of the large Neotropical genus Philodendron (Araceae): Accelerated speciation in a lineage dominated by epiphytes

“…Plastid group II introns of petD , rpl16 , and trnK , including the matK coding region, were selected on the basis of their utility at both deep and shallow phylogenetic levels in angiosperms (Kelchner, ; Borsch and Quandt, ). The petD region has not yet been used in phylogenetic analyses of Philodendron , and only short fragments of the rpl16 intron (~500 bp) and trnK/matK (~450–1600 bp) have been used to date (Gauthier et al., ; Loss‐Oliveira et al., ). The petD and rpl16 regions were amplified and sequenced by adding M13 tails to the amplification primers (Messing, ).…”

“…In the Araceae, Philodendron is one of the most diverse genera in terms of both leaf morphology and life forms—the genus includes terrestrials, vines, hemiepiphytes, and epiphytes (Croat, ; Croat et al., ). Despite the significant contribution of Philodendron to vascular epiphyte diversity in the Neotropics, phylogenetic studies to date have been based on limited taxon sampling and have resulted in partially resolved phylogenetic trees (Barabé et al., ; Gauthier et al., ; Loss‐Oliveira et al., ).…”

“…(; based on ETS and ITS) and Loss‐Oliveira et al. (; based on ETS, matK , trnL , and trnL‐trnF ) recovered the entire genus Philodendron as a monophyletic group sister to Adelonema .…”

“…There are three subgenera in Philodendron that are morphologically and anatomically distinct from each other: subgenus Meconostigma Engl., subgenus Philodendron Schott, and subgenus Pteromischum (Schott) Mayo (Mayo, ; Croat, ; Croat et al., ). The relationships among them, however, remain uncertain (Gauthier et al., ; Loss‐Oliveira et al., ). Philodendron subgenus Meconostigma , which has recently been shown to be monophyletic, comprises 21 mostly terrestrial species distributed in Amazonia, the Mata Atlântica, and the Cerrado (Mayo, ; Braucks Calazans et al., ; Fig.…”

“…Loss‐Oliveira et al. () used fixed average substitution rates of plastid coding regions estimated in monocots to infer ages of Philodendron , and suggested that Homalomena diverged from its sister clade comprising Adelonema and Philodendron in the middle to late Miocene (95% HPD: 9.2–12.8, median age not given) and that Philodendron originated ~8.6 mya (95% HPD: 6.8–12.1). In both of the above studies, however, the nodes critical for inferring the closest extant relatives of Philodendron are not well supported.…”